## The Professor's Cube

### VIII. Solve the Bottom Outer Edges

Sorry to say but hands down, this is the most confusing part of the solution. If you can guide your way out of this section, then the rest will just be a walk through the park.

The remaining 8 outer-edges are already on the bottom layer, and chances are they are pretty much scrambled. The first step is to arrange them in the correct positions. Randomly choose a front side, and proceed to solve the back edges; starting with the back-left edge first and the back-right edge second.

Note: these diagrams look strange. The first one appears to take 4 outer-edges and cram them into one. What the first diagram actually means is that if an outer-edge cube is coming from the left or right sides, then you must repeat the sequence until it appears in the back-left edge. You may have to repeat this sequence four times before that happens.

The second diagram represents any outer-edge from the front side moving to the back-left edge. You may have to repeat that squence twice before it lands there. The dark squares on both diagrams are edges cubes that do not move at all during the process.

Now continue to...

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## M- B2 M+ B-M- B- M+ O- B2 O+ B+O- B+ O+

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### Bottom View

Now continue to...

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## O- B2 O+ B+O- B+ O+ M- B2 M+ B-M- B- M+

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### Bottom View

If you are lucky, the outer-edges going to the back are already paired. You can still move them one at a time, or you can use these shortcuts:

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## M- B- M+ B2M- B- M+ O- B+ O+ B2O- B+ O+

All sequences only have to be performed once to accomplish the move.

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#### ...and solve the "other" back side.

Once again, you have to use the same sequences as before, except this time, the outer-edges are coming from the sides only.

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## M- B- M+ B2M- B- M+ O- B+ O+ B2O- B+ O+

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#### ...and solve the back side again.

This time, you only have to use the sequences that move the outer-edges from the front to the back:

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## M- M- B2M- M- B2M- M- (1 time only)

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Once you solve the back side (for the third time), the remaining 2 outer-edges are forced to the front side, where they belong! Therefore, all 8 bottom outer-edges are in place. Now for the next step: INVERSION.

### Inversion

There are 5 different inversion schemes:

#### Invert 2 outer-edge pairs on adjacent sides Invert 2 outer-edge pairs on opposite sides Invert 4 outer-edge pairs Invert 3 outer-edge pairs Invert 1 outer-edge pair

For each inversion scheme, you must rotate the entire puzzle so that the inverted edge-pairs are positioned exactly like the ones in the diagrams, before attempting the sequence of moves!

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## M- B- M- B2M- B2 M+ B+ M+ O- B- O- B2O- B2 O+ B+ O+ M- B- M- B2M- B2 M+ B+ M+

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#### Result:Two adjacent edge-pairs are still inverted.Go back to Case #1, do the sequence, and thebottom edges are solved.

As it turns out, only two different sequences were used throughout all five cases.
Now that the bottom outer-edges are solved, the next thing to tackle are the
Bottom Inner-Edges.